Electrically actuated clutch brake apparatus

ABSTRACT

There is provided a clutch/brake unit having aligned input and output shafts, clutch disks partially immersed in oil carried by the input shaft, brake disks partially immersed in oil fixed to the housing, and two series of friction disks also partially immersed in oil each series of friction discs secured to the output shaft and each series engagable by separate DC voltage coils. A fan is provided which is rotatable with the input shaft to provide cooling air to the clutch/brake unit. The operation of the clutch/brake unit is controlled by a computer which controls the relationship of the output shafts speed in relation to time.

This is a continuation of U.S. patent application Ser. No. 07/920,261,filed Jul. 27, 1992 and now U.S. Pat. No. 5,291,977.

BACKGROUND OF THE INVENTION

The present invention relates generally to a combination clutch/brakeunit. More particularly, the present invention relates to a new andimproved oil shear clutch/brake unit having frictionally engagableclutch and brake plates and disks which are at least partially immersedin a bath of oil so that the kinetic energy produced in starting andstopping heavy loads is transmitted by "shearing" the oil between thevarious plates and disks. It has been found that this type of immersionincreases the life of the friction elements over those in clutch andbrake units which operate dry. The oil immersion type of clutch andbrake unit also increases the maximum operating speeds.

Clutch/brake units of various types have long been employed to transmitrotational energy between a power source and equipment to be driventhereby. Such units are generally employed so as to provide means foralternately starting and stopping such driven equipment. The inclusionof the braking feature enables more rapid deceleration of the outputshaft than that provided by friction alone. When it becomes necessary toaccurately position a machine, machine tool or work piece, a servo hasbeen employed. Along with the servo comes the problems associated withservos including the servo's complexity and specialized maintenance.

It is accordingly a general object of the present invention to provide anew and improved clutch/brake unit.

It is another object of the present invention to provide a new andimproved clutch/brake unit that utilizes a plurality of oil submergedfriction disk torque transmitting elements which will exhibit a minimalmount of wear by virtue of the fact that the torque transmittingfunction is achieved by the shearing of oil interjacent the disks.

It is still another object of the present invention to provide a new andimproved clutch/brake unit of the above character that can be operatedat high speeds and at high cycle rates as a result of a low driveinertia and an effective oil cooling medium.

It is a further object of the present invention to provide aclutch/brake unit wherein the clutch and brake functions areelectronically controlled and able to emulate a servo without theservo's complexity and specialized maintenance.

It is another object of the present invention to provide a new andimproved clutch/brake unit that will find universality of application.

Further important objects of the present invention are to provide a newand improved clutch/brake unit which is simple in design, economical toproduce and operate, extremely rugged and maintenance-free duringoperation, and wherein the input and output shafts thereof are readilyadapted for mounting to any associated machine, gears, sheaves,couplings, etc.

Other objects and advantages of the present invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal side elevation view, partially in crosssection, of a clutch brake unit of the present invention.

FIG. 2 is an end view of the clutch/brake unit of FIG. 1 taken in thedirection of arrow 2.

FIG. 3 is an end view of the clutch/brake unit of FIG. 1 taken indirection of arrow 3.

FIG. 4 is a plan view of the clutch/brake unit of FIG. 1.

FIG. 5 is a motion diagram of a typical cycle which can be obtainedutilizing the clutch/brake unit of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 through 4 show a clutch/brake unit in accordance with thepresent invention and is designated by the reference numeral 10. Theclutch/brake unit 10 comprises input shaft 12, homing assembly 14,clutch 16, drive brake 18, output shaft 20 and a controlling computer(not shown) which is in communication with an encoder 22 for determiningthe position of the driven equipment.

Input shaft 12 is driven at one end 30 at a specified speed by a twospeed drive motor (not shown). A high-speed potentiometer and alow-speed potentiometer adjust the high and low operating speeds of themotor through a simple digital frequency converter. The two speed drivemotor can be connected to the input shaft 12 by a flexible coupling,drive belts or any other connection means known in the art. In theembodiment shown in FIGS. 1-3, end 30 of the input shaft 12 is providedwith a female spline 32 to facilitate connection to the two speed drivemotor. Input shaft 12 is rotatably disposed within housing assembly 14by a roller bearing 34. The end of the input shaft opposite the driveend 30 defines a first cylindrical shaped chamber 38 and a secondcylindrical shaped chamber 40. Disposed within first cylindrical shapedchamber 38 is a seal 42 for isolating female spline 32 and a rollerbeating 44 for supporting the output shaft 20 as will be explained laterherein. Second cylindrical shaped chamber 38 has an internal surface 46which is adapted with a plurality of axially extending splines 48 tosupport a plurality of driving clutch plates 168 of the clutch 16 aswill be described later herein.

Housing assembly 14 comprises a fan housing 60, a bearing seal ,housing62, a clutch housing 64, a clutch/brake control housing 66 and a brakehousing 68.

Fan housing 60 is generally cylindrical in shape and has a single endwall 70 which partially defines an interior cavity 72. End wall 70 has acircular opening 74 provided therein to allow access to the input shaft12 by the two speed drive motor. Disposed radially outward from thelarge opening 74 are a plurality of circumferentially spaced mountingholes 76 for securing the fan housing 60 to the two speed drive motor.The end of the fan housing 60 opposite to the end wall 70 is adapted tobe fixedly secured to the clutch housing 64. Disposed within interiorcavity 72 is fan 78 which is fixedly mounted to input shaft 12 forrotation therewith. Fan housing 60 has a plurality of air inletapertures 80 which allow for passage of cooling air being pumped by fan78.

Clutch housing 64 is adapted at one end to be fixedly secured to fanhousing 60 by a plurality of circumferentially spaced mounting bolts 82.The opposite end of the clutch housing 64 is adapted to be fixedly andsealably attached to clutch/brake control housing 66. Clutch housing 64is generally cylindrical in shape and has a single end wall 84 adjacentthe end of the control housing 64 adapted to mate with fan housing 60.End wall 84 completes the formation of interior cavity 72 and partiallyforms a second interior cavity 86. Disposed within second interiorcavity 86 is the first and second cylindrical shaped chambers 38 and 40of the input shaft 12. End wall 84 further defines inner cylindricalsurface 88 which supports miter bearing 34 and forms a locating surfacefor bearing seal housing 62. The interface between the fan housing 70and the beating seal housing 62 defines a plurality of air outletapertures 90 which allow for passage of cooling air being pumped by fan78. The air outlet apertures 90 cooperate with the air inlet apertures80 to create a path for air pumped by fan 78 to flow across clutchhousing 64 and aid in the cooling of oil disposed within second interiorcavity 86. The bearing seal housing 62 is adapted to be fixedly andsealably attached to clutch housing 64 by a plurality ofcircumferentially spaced bolts 92 and seal 94. Bearing seal housing 62is located by inner cylindrical surface 88 and locates an additionalseal 96 relative to input shaft 12. Seal 96 rides against input shaft 12and seals the oil disposed within second interior cavity 86.

Clutch/brake control housing 66 is an annular shaped housing having aflange 91 disposed on its exterior surface, midway between each end.Flange 91 has a first plurality of mounting holes 93 for securingclutch/brake control housing 66 to clutch housing 64 using a pluralityof bolts 97 and is sealed by seal 98. Flange 90 further has a secondplurality of mounting holes 95 for securing clutch/brake control homing66 to brake homing 68. The interior portion of clutch/brake controlhoming 66 defines a continuation of second interior

Disposed within the annular portion of clutch/brake control housing 66is a clutch coil cavity 100 which is located in the end of theclutch/brake control housing 66 adjacent to the clutch housing 64 and abrake coil cavity 104 which is located in the end of the clutch/brakecontrol housing 66 adjacent to the brake housing 68. Disposed withinclutch coil cavity 100 is a DC voltage clutch coil 102 and disposedwithin brake coil cavity 104 is a DC voltage brake coil 106. A pluralityof circumferentially spaced spring bores 108 are also located in theannular portion of clutch/brake control housing 66 radially inward fromclutch and brake coil cavities 100 and 104 and extend completely throughclutch]brake control homing 66. Disposed within the plurality ofcircumferentially spaced spring bores 108 are a plurality of coilsprings 110.

An annular clutch pressure plate 112, located between input shaft 12 andclutch/brake control housing 16, is axially aligned with the annularclutch/brake control housing 16 and is in contact with one end of theplurality of coil springs 110. Clutch pressure plate 112 is located inan annular recess 114 of clutch homing 64 such that it is capable ofmoving axially. Clutch pressure plate 112 has an axially extendingcylindrical portion 116 which has an exterior surface 118 for locating aroller bearing 120 which rotatably mounts a clutch activation member 122which provides the means for engaging and disengaging clutch 16. Theplurality of coil springs 110 urge clutch pressure plate 112 and clutchactivation member 122 axially to the left as shown in FIG. 1. In thisposition, clutch 16 is in the engaged position. Upon activation of DCvoltage clutch coil 102, clutch pressure plate 112 and clutch activationmember 122 are magnetically attracted to clutch/brake control housing 66and move axially to the right as shown in FIG. 1. The magneticattraction of DC voltage clutch coil 102 overcomes the spring force ofthe plurality of coil springs 110 and clutch 16 is disengaged. When thepower to DC voltage clutch coil 102 is terminated, the plurality), ofcoil springs 110 urge clutch pressure plate 112 to the left as shown inFIG. 1, again engaging clutch 16.

An annular drive brake pressure plate 132, located on the side ofclutch/brake control housing 66 adjacent brake homing 68 is axiallyaligned with annular clutch/brake control housing 16 and is in contactwith the second end of the plurality of coil springs 110. Drive brakepressure plate 132 is located in an annular recess 134 of brake housing68 such that it is capable of moving axially. Drive brake pressure plate132 has an axially extending cylindrical ring 136 which provides themeans for applying and releasing drive brake 18. The plurality of coilsprings 110 urge the brake pressure plate 132 axially to the right asshown in FIG. 1. In this position, drive brake 18 is in the appliedcondition. Upon activation of DC voltage brake coil 106, drive brakepressure plate 132 is magnetically attracted to clutch/brake controlhoming 66 and moves axially to the left as shown in FIG. 1. The magneticattraction of DC voltage brake coil 106 overcomes the spring forces ofthe plurality of coil springs 110 and brake 18 is released. When thepower to DC voltage brake coil 106 is terminated, the plurality of coilsprings 110 urge drive brake pressure plate 132 to the right as shown inFIG. 1, again applying brake 18.

Brake housing 68 is generally cylindrical in shape and is adapted at oneend to be fixedly secured to clutch/brake housing 66 by a plurality ofcircumferentially spaced mounting bolts 140 and is sealed by seal 142.The opposite end of brake housing 64 has an end wall 144 which completesthe formation of second interior cavity 86. End wall 144 further definesan inner cylindrical surface 146 which supports roller bearing 148 andforms a locating surface for seal 150. The outside of end wall 144 has aplurality of mounting holes 152 which facilitate the attachment ofclutch/brake unit 10 to the driven apparatus (not shown). Brake housing68 also has an axially extending cylindrical portion 154 extendingtowards input shaft 12. The extending cylindrical portion 154 has aninternal surface 156 which is adapted with a plurality of splines 157 tosupport a plurality of reaction brake plates 184 of brake 18.

Output shaft 20 is rotatable mounted in roller bearings 44 and 148 andextends axially from roller bearing 44 located in first cylindricalchamber 38 of input shaft 12 through clutch housing 64, throughclutch/brake control housing 66, through brake housing 68 and extendsaxially past brake housing 68. The end of output shaft 20 extendingbeyond brake housing 68 is adapted to be secured to the driven apparatus(not shown). Located axially along the output shaft 20 are a clutchmounting area 160 and a drive brake mounting area 162. Output shaft 20has a seal surface 158 upon which seal 150, which is located in brakehousing 68, rides against to seal second internal cavity 86. Secondinternal cavity 86 contains a quantity of lubricating oil whichlubricates roller bearings 34, 44, 120 and 148 as well as providing thenecessary oil for the oil shear action of clutch 16 and brake 18.

Clutch 16 is an oil shear clutch which comprises a clutch disk supportmember 164, a plurality of driven clutch plates 166 and the plurality ofdriving clutch plates 168. Clutch disk support member 164 is fixedlymounted to output shaft 16 in clutch mounting area 160 such that itrotates with output shaft 16. Clutch disk support member 164 ispositioned against shoulder 170 on output shaft 20 and is held inposition by snap ring 172. The outer surface of clutch disk supportmember 164 is provided with a plurality of axially extending splines 174for connecting engagement with associated notches formed in the innerperiphery of the plurality of driven clutch plates 166. The plurality ofdriven clutch plates 166 are free to move axially between an annularclutch friction plate 174 secured to input shaft 12 and clutch actuationmember 122.

The plurality of driving clutch plates 168 are disposed interjacent orinterleaved between the plurality of driven clutch plates 166 and areprovided with notches on their outer periphery for connecting engagementwith splines 48 of input shaft 12. The plurality of driving clutchplates 168 are also free to move axially between clutch friction plate174 and clutch actuation member 122.

In operation, the plurality of coil springs 110 normally bias the clutchactuation member 122 to the left as shown in FIG. 1. This biasing ofclutch actuation member 122 to the left, as shown in FIG. 1, causes thedriving clutch plates 168 and driven clutch plates 166 to be clampedtogether between clutch friction plate 174 and clutch actuation member122 thus locking the input shaft to the output shaft for rotationtogether. When DC voltage is applied to DC voltage clutch coil 102,driving clutch plates 168 and driven clutch plates 166 are free torotate relative to each other whereby input shaft 12 is free to rotaterelative to output shaft 20. When the DC voltage is removed from clutchcoil 102, the plurality of coil springs 110 again clamp the driving anddriven clutch plates 168 and 166 together locking input shaft 12 tooutput shaft 20.

Drive brake 20 is an oil shear brake which comprises a drive brake disksupport member 180, a plurality of driving brake plates 182 and theplurality of reaction brake plates 184. Drive brake disk support member180 is fixedly mounted to output shaft 20 in drive brake mounting area162 such that it rotates with output shaft 16. Drive brake disk supportmember 180 is held in position by snap ring 188. The outer surface ofbrake disk support member 180 is provided with a plurality of axiallyextending splines 190 for connecting engagement with associated notchesformed in the inner periphery of the plurality of driving brake plates182. The plurality of driving brake plates 182 are free to move axiallybetween an annular brake reaction plate 192 secured to brake housing 68and brake actuation ring 136 extending from brake pressure plate 132.

The plurality of reaction brake plates 184 are disposed interjacent orinterleaved between the plurality of driving brake plates 182 and areprovided with notches on their outer periphery for connecting engagementwith splines 157 of brake housing 68. The plurality of reaction brakeplates 184 are also free to move axially between brake reaction plate192 and brake reaction ring 136.

In operation, the plurality of coil springs 110 normally bias brakepressure plate 132 and brake reaction ring 136 to the right as shown inFIG. 1. This biasing of brake reaction ring 136 to the right as shown inFIG. 1, causes the driving brake plates 182 and reaction brake plates184 to be clamped together between brake reaction plate 192 and brakereaction ring 136 thus locking output shaft 20 to brake housing 68 andprohibiting rotation thereof. When DC voltage is applied to DC voltagebrake coil 106, driving brake plates 182 are free to rotate relative tothe reaction brake plates 184 whereby output shaft 20 is free to rotaterelative to brake housing 68. When DC voltage is removed from brake coil106, the plurality of springs 110 again clamp driving and reaction brakeplates 182 and 184 together locking output shaft 20 to brake housing 68.

Encoder 22 is secured to housing assembly 14 by using an adaptor 200which is bolted to housing assembly 14 by a plurality of bolts (notshown). Encoder 22 receives its rotational information via a pulley 204fixedly secured to output shaft 20, a pulley 206 fixedly secured toencoder 22 and a drive belt 208 connecting pulleys 204 and 206. Encoder22 has an output of 2000 counts per revolution. A 4-times dividercircuit increases the effective counts to 8000 counts per revolution.Thus the encoder is capable of accurately predicting the rotativeposition of the output shaft which in turn identifies the position ofthe driven apparatus.

The motion diagram in FIG. 5 represents a typical motion curveachievable with the clutch/brake unit of the present invention whendriven by the two speed drive motor. The motion diagram in FIG. 5comprises five stages of motion, an initial acceleration stage 300, ahigh speed stage 302, a high speed deceleration stage 304, a low speedstage 306 and a low speed deceleration stage 308. The start position 310and the stop position 312 are fixed. The controlling computer must be"taught" where the high speed stage 302 ends, point 314 in FIG. 5, andwhere the low speed stage 306 ends, point 316 in FIG. 5. In addition,the controlling computer must be given both the acceleration anddeceleration rates for stages 300 and 304.

The acceleration rate for stage 300 is controlled by clutch 16 bychanging the DC voltage applied to clutch coil 102. The time (inseconds) desired to accelerate the machine to high speed is entered intothe control computer while the control computer is in the LEARN mode. Ina similar manner, the deceleration rate of stage 304 is controlled bydrive brake 18 by changing the DC voltage applied to brake coil 106. Thetime (in seconds) desired to decelerate the machine from high speed tolow speed is also entered into the control computer while the controlcomputer is in the LEARN mode. The rate of deceleration does not have tobe the same as the rate of acceleration.

The point 314 where high speed travel ends and point 316 where low speedtravel ends can either be entered into the computer by jogging the driveto those respective positions and entering them into the controlcomputer during the LEARN mode by pushing the appropriate button or theycan entered in digital counts as would be with a servo. Multiple slowspeed and stop positions can be entered.

Once the initial information has been "taught" to the control computer,the machine is cycled five times while in the LEARN mode. During thefive LEARN mode cycles, the control computer determines the mount of DCvoltage which is required to be supplied to the coils 102 and 106 inorder to achieve the desired rates of acceleration and decelerationrespectively. Thus, the control computer has the capability ofself-adjusting the rate of applying the DC voltage to meet the bothcoils 102 and 106 specified speed/time relationship.

The operation of the cycle begins with power being supplied to the twospeed drive motor through a high speed potentiometer thus operating thetwo speed drive motor at high speed driving input shaft 12. Clutch 16 isin the disengaged position and drive brake 18 is in the appliedcondition due to full voltage being applied to clutch coil 102 and novoltage being applied to brake coil 106. Simultaneously, the controlcomputer applies full voltage to brake coil 106 and systematicallyreduces the voltage to clutch coil 102 thus releasing drive brake 18 andengaging clutch 16 which accelerates the output shaft 20 according tothe pre-programmed acceleration stage 300 shown in FIG. 5. Because a DCvoltage coil is used for clutch oil 102, it is possible to adjust theslope of the acceleration curve to suit a particular requirement. Therate of acceleration stage 300 is controlled by the rate of decreasingthe DC voltage to clutch coil 102 from full voltage to 0 voltage.

The high speed stage 302 occurs when the two speed drive motor isoperating at full speed, clutch 16 is engaged, and drive brake 18 isreleased. The high speed stage 302 continues until the pre-programmedhigh speed deceleration position, point 314, is reached. At this point,the control computer disconnects power to the two speed drive motor andsystematically reduces the DC voltage to brake coil 106 thus applyingdrive brake 18 which decelerates output shaft 20 according to thepre-programmed deceleration stage 304 shown in FIG. 5. Brake coil 106 isalso a DC voltage coil so it is therefore possible to adjust the slopeof the deceleration curve to suit a particular requirement. The rate ofdeceleration stage 304 is controlled by the rate of decreasing the DCvoltage to brake coil 106 from full voltage to 0 voltage.

When the speed of output shaft 20 has been reduced to coincide with thelow speed capabilities of the two speed drive motor, the power to thetwo speed drive motor is supplied through a low speed potentiometer thusoperating the two speed drive motor at a reduced speed. Clutch 16 is inthe disengaged position due to a lack of voltage being applied to clutchcoil 102 and full voltage is again applied to the brake coil 106 thusreleasing drive brake 18 and allowing output shaft 20 to rotate at thereduced speed of the two speed drive motor. This condition isrepresented by low speed stage 306 shown in FIG. 5.

The low speed stage 306 continues until the pre-programmed low speeddeceleration position, point 316, is reached and low speed decelerationstage 308 is entered. At this point, the controlling computerdisconnects the power from the two speed drive motor and removes the DCvoltage from brake coil 106 thus applying drive brake 18 and bringingboth input shaft 12 and output shaft 20 to a stop. In order to begin thecycle again, the power is applied m the two speed drive motor throughthe high speed potentiometer and full voltage is applied to clutch coil102 thus allowing input shaft 12 to rotate with the high speed drivemotor independent of output shaft 20.

While the above detailed description describes the preferred embodimentof the present invention, it is to be understood that the presentinvention is susceptible to modification, variation and alterationwithout deviating from the scope and fair meaning of the subjoinedclaims.

What is claimed is:
 1. A drive for an apparatus comprising:a stationaryhousing; output means for transmitting rotation from said drive, saidoutput means rotatably mounted in said housing; input means fortransmitting rotation to said drive, said input means rotatably mountedin said housing; selectively operable brake means for prohibitingrotation of said output means with respect to said housing; selectivelyoperable clutch means for locking said input means to said output means;and means for controlling said selectively operable brake and clutchmeans such that said input means drives said output means between astart position and a stop position along a specified multi-speedprogram, said controlling means being capable of self-adjusting to meetsaid specified multi-speed program.
 2. The clutch/brake drive of claim 1further comprising fan means for moving air around said stationaryhousing.
 3. The clutch/brake drive of claim 1 wherein said output meanscomprises a shaft rotatably mounted in said stationary housing.
 4. Theclutch/brake drive of claim 1 wherein said input means comprises a shaftrotatably mounted in said stationary housing.
 5. The clutch/brake driveof claim 1 wherein said brake means comprises a plurality of interleavedfirst friction disks alternately splined, respectively, to said outputmeans and said stationary housing.
 6. The clutch/brake drive of claim 1wherein said clutch means comprises a plurality of interleaved secondfriction disks alternately splined, respectively, to said input meansand said output means.
 7. The clutch/brake drive of claim 1 wherein saidclutch means is movable to a released condition by a DC voltage coil. 8.The clutch/brake drive of claim 1 wherein said brake means is movable toa disengaged condition by a DC voltage coil.
 9. The clutch/brake driveof claim 1 wherein said controlling means comprises:an encoder operablyassociated with said output means for determining the rotative positionof said output means; computer means in communication with said encoderfor selectively controlling said apparatus, said brake means and saidclutch means such that said drive means drives said machine along saidspecified multi-speed program.